It is well established that H2S is a physiological gaseous mediator in humans and animals. More recently, it has also been found that H2S is a gaseous mediator in plants (M. Lisjak et al, Plant Physiol. Biochem., 2010, 48(12), 931-5).
In humans and animals, H2S is synthesised primarily from L-cysteine and homocysteine from the pyridoxal phosphate-dependent enzymes cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE). At present, it is thought that CBS is found primarily in nervous tissue, whereas CSE is expressed in vascular and inflammatory cells (M. Whiteman et al, J. Cell Mol. Med., 2009; 13:488-507; and M. Whiteman et al, Expert Reviews in Clinical Pharmacology, 2011, 4, 13-32). The generation of H2S in human and other mammalian tissues is likely to occur at a slow and constant rate, and it appears to be involved in several processes, such as hypertension, inflammation, edema and hemorrhagic shock (G. Caliendo et al, J. Med. Chem., 2010, 53(17), 6275-6286). Compounds that are able to slowly release H2S in vivo are therefore likely to have therapeutic applications in the treatment of diseases or disorders involving such processes.
It has also been found that compounds that are able to slowly release hydrogen sulfide in vivo are able to prevent stomatal closure in plants (M. Lisjak et al, Plant Physiol. Biochem., 2010, 48(12), 931-5). Compounds that slowly release H2S in vivo in plants may promote plant growth or can be used as a herbicidal treatment.